Composition and method for dust suppression wetting agent

ABSTRACT

This disclosure teaches a composition and process which makes it possible to remove floating particulates or prevent the dissemination or particulates, by the misting of a solution that readily captures any particulate material in the air. More specifically, the present disclosure teaches the composition and use of aromatic compounds that are semi-volatile organic compounds (SVOCs) or slow evaporators in water-based carriers with surfactants as the misting/fogging agent for dust suppression. The particulate material is lowered to surfaces and removed by vacuuming, damp-wiping or using a dry cloth with a cationic charge (static cloth). This method can be achieved with neutral air pressure differentials in the work areas.

FIELD OF THE DISCLOSURE

This disclosure is a new method for controlling dust or particulates,such as asbestos or inert biological materials, in contained oruncontained areas during remediation or renovation activities.

BACKGROUND OF THE DISCLOSURE

Up until 1974, asbestos had been respected and used in industry due toits excellent incombustible and refractory properties, heat-insulatingproperties, and sound-absorbing qualities. Normally, asbestos wasincorporated on walls, pipes, and industrial equipment in schools,residences, factories, office buildings, ships, and older motorvehicles, whenever sound, heat, or fire proofing was required.

However, over time, asbestos fibers tend to become airborne, as thesurface spray coated with asbestos is vibrated or an object collidesagainst the asbestos-coated surface or when the binder used in thecoating deteriorates. Often, and perhaps most commonly, asbestos fibersfill the air when a building is renovated or demolished. The problemwith asbestos fibers filling the air is that the fibers areenvironmentally hazardous, and, if inhaled, may cause asbestosis,mesothelioma or lung cancer. Thus, there is an urgent need to removeasbestos in tens of thousands, and perhaps hundreds of thousands, ofbuildings nationwide. Internationally, there are many millions ofbuildings from which asbestos must be removed. This will lead to manycases wherein asbestos fibers become airborne, often in an enclosedroom, thereby causing a health hazard to many thousands of people.

In the past, asbestos containing materials was removed by workerswearing dust respirators and dustproof clothes. There have been a numberof different methods used to remove asbestos. Asbestos layer(s) wereremoved by rod-type scrapers or wire brushes while spraying a wettingagent or amended water on the building material to be removed in asealed workroom made for the removal operation. Another method ofasbestos removal involves solidifying the surface of the asbestoscoating by the use of a resin or a liquid chemical to encapsulate. Inyet another method, asbestos-coated surfaces are enclosed with boards orthe like.

While the latter two methods described above are merely temporarymeasures, the first-mentioned method comprising physical removal ofasbestos is, in fact, a permanent solution. However, the manual removalof asbestos by use of rod-type scrapers or wire brushes requires muchlabor and leads to high working expenses due to the need to have aperson spraying a wetting agent for dust suppression for each personremoving building material. Most importantly, asbestos fibers generatedin the removal operation are suspended in air for a long time, and thesealed workroom must be left sealed for a long time. Forced removal ofthe suspended asbestos fibers requires the use of HEPA filters and alarge-capacity dust collector, leading to extremely high workingexpenses. Additionally, the manual removal of asbestos by the workershas the problem that many portions of asbestos tend to be leftunstripped, particularly at narrow areas near corners or the existingpiping, and the portions of asbestos left unstripped may scale offlater. Furthermore, even with the use of the dust collector, a smallamount of the asbestos fibers separated from the original surface mayremain in air or accumulate at the corners of the floor, the asbestosfibers being very difficult to collect.

Dust suppression is used to clean the air of particulate matter. Theparticulate can be inorganic material such as asbestos (chrysotile,amosite, crocidolite, tremolite, actinolite, anthrophyllite, etc.),asbestiform minerals, silica, metals, salts or manmade polymers such asnylon, plastic, fiberglass, nanoparticles, etc. Particulate matter canalso originate from biological materials such as germs, insects, plants,animal based allergens, proteomic proteins of health concerns, etc. Theparticles can be from 1 micron to 50 microns or smaller which ismeasured in nanometers. 1 micron equals 1,000 nanometers.

Various dust suppressant compositions and methods are known in the artfor spraying in air to reduce air-borne dust or for spraying onsubstances which develop dust.

U.S. Pat. No. 4,369,121 (Callahan et al.) discloses a composition forcontrolling dust which comprises a cellulose ether and a wetting agentsuch as an ethylene oxide condensate of nonyl- or octylphenol, ethyleneoxide condensates of straight chain alcohol, fatty acid amides,quaternary ammonium compounds, organic phosphate esters, and sulfonicacids.

U.S. Pat. No. 4,169,170 (Doeksen) discloses a composition and method forcontrolling dust during coal transportation wherein the compositioncomprises an aqueous solution containing an asphalt emulsion or a blackliquor lignin product and a water soluble ethoxylated alkyl phenol.

U.S. Pat. No. 4,425,252 (Cargle et al) discloses an aqueous coal dustabatement composition including a water soluble sulfonic acid salt andethoxylated nonyl phenol.

U.S. Pat. No. 4,428,984 (Shimizu et al) discloses a method of preventingdusts by spreading an aqueous solution including an ethoxylated alkylphenol, alcohol, fatty acid, amine or fatty acid amide and a polyhydricalcohol.

U.S. Pat. No. 4,487,615 (Taylor et al.) discloses a method of reducingmine dust by spraying water including a surfactant produced by reactingethylene oxide with linear primary alcohols.

U.S. Pat. No. 4,136,050 (Brehm) and U.S. Pat. No. 4,171,276 (Brehm)disclose a dust suppression composition comprising an aqueous solutionof alkyl phenoxy polyethoxy ethanol and a copolymer of ethylene oxideand propylene oxide.

U.S. Pat. No. 5,052,756 (Wada et al.) discloses a process for separationof an asbestos-containing material from a surface to which theasbestos-containing material is adhered, while preventing floating ofdust of the removed asbestos-containing material. The process requiresjetting of pressurized water from a plurality of nozzles to the surfaceat a pressure of at least 80 kg/cm.sup.2 so as to wet and remove theasbestos-containing material therefrom by the energy possessed by thepressurized water.

Dust suppression for interior spaces is generally accomplished by usinga combination of engineering controls and a misting agent. Mistingagents are sometimes referred to as “amended water” or water with asurfactant. The term “amended water” comes from 29 CFR 1926.1101 or theOSHA regulations for asbestos in construction. Fogging is another termused in some applications common to greenhouses and cleanrooms wherepesticides are administered.

The air is misted with the misting agent. The water droplets from themisting agent adhere to the particulate material in the air that is theoffending agent to health or the environment. This increases the weightof the particulate material. This forces the particulate material todrop to surfaces due to the increased weight or specific gravity. Thisallows the particulate materials to be removed by cleaning methods onsurfaces or to be “locked down” to a surface (such as a floor or wall)with a paint or sealer so the particles are permanently adhere to thesurfaces.

The problem with the first scenario is that the misting agent must notevaporate too quickly or the particulate material will become airborneagain. The problem with the second scenario of the particulate materialsis that the asbestos needs to be removed rather than hidden under apaint, glue or polymer film that may be disturbed during a futurerenovation or catastrophic event like fire, flood, etc.

In each circumstance, the offending agent or particulate is removed fromthe air to prevent the particulate from entering the respiratory tractand possibly the bloodstream. Environmental controls use techniques suchas pressurization (positive and/or negative) differentials of acontained area and mechanically exhausted through a HEPA filter and/orwater baffle. This is largely done to limit cross-contamination duringthe removal of the particulate material or offending agent.

Towards that end many of the techniques involve the use of “negative airpressure differential” conditions, which are not desirable because the“amended water” droplets are pulled out of the contained area tooquickly and the surfaces dry too quickly to capture particleseffectively.

The contained area is usually “flooded” with amended water in an attemptto ensure particle capture. It takes a high amount of the “amendedwater” due to the use of the negative air pressure machines. The jobsite becomes awash in water that must be constantly removed. The area issaturated, sometimes causing water damage to the non-remediated areas.Microbial growth is encouraged by the high-humidity conditions broughtabout by traditional methods.

The above dust suppressing compositions and methods all have variousdisadvantages in that the compositions are not immediately effective andrequire an extended time for satisfactory performance or that thecompositions include excessively toxic or other less biodegradablematerials.

There is therefore a need for a dust suppressant composition whichquickly enhances the settling of air-borne dust and which issubstantially biodegradable and benign in the environment.

SUMMARY OF THE DISCLOSURE

Accordingly, this disclosure teaches a composition and process whichmakes it possible to remove floating particulates or prevent thedissemination or particulates, by the misting of a solution that readilycaptures any particulate material in the air.

More specifically, the present disclosure teaches the composition anduse of aromatic compounds that are semi-volatile organic compounds(SVOCs) or slow evaporators in water-based carriers with surfactants asthe misting/fogging agent for dust suppression. The particulate materialis lowered to surfaces and removed by vacuuming, damp-wiping or using adry cloth with a cationic charge (static cloth).

For the purposes of this application, a semi-volatile organic compound(SVOC) is an organic compound which has a boiling point higher thanwater and which may vaporize when exposed to room temperature (orhigher).

Misting or fogging with this type of agent replaces traditional “amendedwater” spraying during dust-producing activities. This method relies onthe slow-evaporating misting agent's ability to capture and holdparticles long enough to be captured by wiping or vacuuming. Thisdisclosure is more economical, environmentally preferable or green andmore efficient than current methods or uses.

In another embodiment of the disclosure, dust suppression is performedunder “neutral air pressure differential” conditions because the “mist”or “fog” should remain suspended in the air for a sufficient time tocapture particles.

In one embodiment of this disclosure, particles as low as 10 nanometerscan be captured and removed.

In yet another embodiment of the disclosure, surfactants are used tohelp keep the water tension at a desirable level to bind the particulatematerials.

DETAILED DESCRIPTION OF THE DISCLOSURE

Following or during the removal of asbestos or dust laden materialsduring the renovation or demolition of a building, ship, or machinery, afine mist or spray should use the composition containing thesemi-volatile organic compounds which is preferably applied to suppressand trap asbestos, dust, and other airborne particles.

More specifically, these SVOC, aromatic compounds include but notlimited to: phenols, phenyls, benzyls, glycols, glycerol, butadienes,carboxyl groups, terpenes, phthalates, anthracenes, isophorenes, plantesters, ketones, amines, glycol ethers, pyrenes, toluenes, heterocycliccompounds, polycyclic aromatic hydrocarbons, mono and di aromatics,polyols, xanthenes, plant essential oils, enzymes from microbes, etc,and combinations thereof. The most preferred compounds are phenol,sodium phenate and glycerol. However, the choice of SVOCs may bedependent on humidity, temperature, overall climate, material beingremoved, gallons per hour of mist spray, cubic feet of air beingcleaned, etc. Also, a mixture of SVOC's may be used, so that differentparticles of different sizes and charges may be captured. A preferredmixture of SVOC's may include phenol: 1.56%, and sodium phenate: 0.06%

The SVOCs may comprise from between about 0.25% and about 20% of amixture by weight, with a preferable range of between about 0.25% andabout 10%.

The use of these compounds will require respirators that have filtersrated by CDC NIOSH for “organic vapors” to follow OSHA regulations.

The mixture also contains surfactants and/or detergents to help keep thewater tension at a desirable level to bind the particulate materials.Surfactants and/or detergents also help emulsify the SVOCs in the watercarrier. The surfactants and/or detergents that are used may be borates,cationic surfactants, anionic surfactants, neutral charged surfactants,amid surfactants, etc. These compounds include but not limited to:Sodium dodecylsulfate (SDS), Sodium deoxycholate (DOC),N-Lauroylsarcosine Sodium salt, LauryIdimethylamine-oxide (LDAO),Cetyltrimethylammoniumbromide (CTAB), Bis(2-ethylhexyl)sulfosuccinateSodium salt, 1-Octanesulfonic acid sodium salt, Sodium1-butanesulfonate, Sodium 1-decanesulfonate, Benzalkonium chloride,Benzethonium chloride,N-Dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate, lignin basedsurfactants, coconut based surfactants, etc. It is preferable to usesodium dodecylsulfate (SDS), as surfactants, and most preferable to usesodium borates. A mixture of cationic surfactants, anionic surfactants,and nonionic surfactants can be used. Overall, the total surfactants canrange from about 0.1% to 3% by weight.

Optionally, other components may be included in the solution. Thesecomponents include

Optimum SVOC % Surfactant/Detergent % Water % Lavender oil: 0.02-2%; 1%,Quaternary Ammonium: 0.25-25%; 25% 73.5% *Glycerol: 0.2-1%; 0.5%*Glycerol: 0.2-1%; 0.5% *Glycerol: 0.2-1%; 0.5%, Benzethonium chloride:0.25-2%; 1%, 97.5% D-limonene: 0.5-2%; 1%, *Glycerol: 0.2-1%; 0.5% Pineoil: 0.25-2%; 1%, Lignin Surfactants 1%, 95.5% Thymol: 0.25-2%; 1%,*Glycerol: 0.2-1%; 0.5% Eucalyptol: 0.25-2%; 1%, *Glycerol: 0.2-1%; 0.5%Phenol: 0.31-2%; 1.56%, SDS: 0.06-0.4%; 0.3%, 97.11%  Sodium phenate:0.01-0.1%; 0.06%, Sodium borate: 0.9-0.55; 0.47%, *Glycerol: 0.2-1%;0.5% *Glycerol: 0.2-1%; 0.5% O-phenylphenol: 0.04-0.3%; 0.22%,Benzethonium chloride: 0.14-0.8%; 0.70%, 98.58%  *Glycerol: 0.2-1%; 0.5%*Glycerol: 0.2-1%; 0.5% Oil of Laurel: 0.25-2%; 1%, Triton 100: 0.1-1%;0.5%   97% Linalool: 0.25-2%; 1%, *Glycerol: 0.2-1%; 0.5% *Glycerol:0.2-1%; 0.5% Each set of numbers starts with a percentage range followedby the optimal percentage after the semicolon *Glycerol is both a SVOCand a surfactant

Water is given in optimum levels but may change with the range used.Perfume agents may be added at approximately 0.05% in place of water.There is little ned for adding emulsifying ingredients since suffacantsand detergents tend to emulsify the SVOC's that are slightly miscible.

There is little need for adding preservative ingredients sincesurfactants, detergents and some SVOCs tend to act as preservatives(examples: Phenols, quaternary ammoniums, etc).

Different combinations of aromatic compounds (SVOCs) and surfactants canbe mixed at small amounts each to achieve the same as large amounts of asingular aromatic SVOC compound and a singular surfactant.

Mixing combinations of compounds may lower toxicity while maintainingthe benefits of the disclosure.

The aromatic compounds are also emulsified so the water molecule(s)slowly evaporate without creating any permanent films like a paint,polymer, plastic, etc. Polarity is only important to the point ofcombining or emulsifying the aromatic chemicals to water in a mannerthat slows the rate of evaporation.

As noted above, a major problem with traditional dust suppressiontechniques is the large amount of “amended water” that must be used dueto the concurrent use of engineering controls such as negative airpressure differential enclosures. This negative air pressure commonlyused in asbestos abatement (OSHA 29 CFR 1926.1101) and microbialremediation (ACGIH) causes many possible misting agents to evaporate tooquickly. These regulations and publications call for a negative pressuredifferential enclosure measured with a manometer at negative 0.02 inchesof water column or greater. This is equal to negative 5 pascals orgreater. Generally this means there is approximately 4 air changes perhour or greater as more air leaves the contained area than enters it.The purpose of the contained area under negative air pressure is to helpprevent cross-contamination at the expense of using more water thannecessary at the expense of our natural resources.

The new method is “environmentally preferable” or “green” due to thesignificant reduction in water usage and electrical usage. First, themisting agent is a slow evaporator. Second, the work areas are containedwith “critical control barriers” and necessary plastic sheeting or othermaterial to prevent migration of contaminants outside the work area.Preferably, the work area is under “neutral” air pressure differentialor between +0.02 to −0.02 inches of water column. Preferably, only theareas under negative air pressure are the decontamination chambers whereworkers remove waste material or their personal protective equipmentbefore passing through the shower between the equipment room and theclean room or entrance/exit. (equipment room, shower)

There are various machines that can be used to mist or fog the air withthe misting agent. It should be noted that there is a difference betweenthe terms “misting” and “fogging”. Fogging is to produce an averagemicron band size of 50 microns or less. Some water droplets will bebelow or above 50 microns but the average size of the droplets will be50 microns in diameter. Misting is producing an average micron range fordroplets above 50 microns. Either type of machine will work for mistingthe air for dust suppression. The fogging approach takes more time tosettle since the water droplets are smaller and float more easily.Misting uses a little more liquid and the larger droplets fall morerapidly. Both types of machines require the use of respirators. The typeof machines to dispense the misting agent are manufactured by FogMaster, B&G, ElectroFan, and Dramm. These types of machines that can beused to mist or fog the misting agent All of the machines generally workthe same way. Each fogger or mister creates enough pressure to dispersethe misting agent at a small droplet size at various volumes per minutethrough one or more orifices, depending on motor sizes and preference.

Hand pumps that are used to dispense pesticides and herbicides thatcould also be used. These inexpensive devices would dispense greateramounts of the misting agent at much larger water droplet sizes withmore labor which would partially offset the “green” benefits as well asreduce labor costs.

On large projects, this lack of a need for large HEPA filtered negativeair machines will greatly reduce electrical usage while helping toreduce the amount of water required by 80% to 95% versus typical mistingprocesses using other reagents or solutions. The amount of the cleaningsolution used varies from project to project, but one gallon of theproposed solution should be create a cloud of water droplets thatcapture particles in an 80,000 cubic feet area when dispensed by a B&Gfogger. The machines generate an aerosol of liquid droplets that adheresto the particulates floating in the air as the droplets descend tohorizontal surfaces. This area coverage amount could be less ifpersonnel wear motor operated air purifying respirators (PAPR) whichhelp supply air through filters to the respirators. The PAPR respiratorswould filter the air next to the motor of the personnel using the PAPRequipment which would necessitate further application of the misting orwetting agent. Also, continual releases of construction material orother particulate generating activities may necessitate further mistingor fogging for this solution. At any rate, the amount of productrequired will be far less in volume than traditional misting or foggingagents that evaporate too quickly.

As the mist removes the particulate material from the air, theparticulate material settles on surfaces. The settled particulatematerial is then removed by HEPA vacuuming, damp-wiping or using a drycloth with a cationic charge (static cloth). For definitional purposes,the HEPA filter is a high efficiency particulate air filter that cancapture particles down to 0.3 microns at a capture rate of 99.97percent. Some HEPA filters are now even more sensitive. Damp wiping canbe done with natural or synthetic fiber based cloths that are damp withany liquid including the misting or fogging agent. The damp wipe clothscan be disposed as waste material or laundered depending on the targetagent removed from the air and surfaces.

While this disclosure has been described with an emphasis upon preferredembodiments, it will be obvious to those of ordinary skill in the artthat variations of the preferred embodiments may be used and that it isintended that the invention may be practiced otherwise than asspecifically described herein. Accordingly, this invention includes allmodifications, alternative constructions, and equivalents encompassedwithin the spirit and the scope of the invention.

1) A method for removing particulate matter from the air, said methodcomprising: a) obtaining a liquid mixture, said liquid mixturecomprising: i) aromatic compounds; and ii) water; b) introducing saidliquid mixture into air of a confine space to remove said particulatematter; and c) removing said liquid mixture that has been sprayed intothe air. 2) The method according to claim 1, wherein said aromaticcompounds are selected from the group consisting of semi-volatileorganic compounds. 3) The method according to claim 1, wherein saidsemi-volatile organic compounds are selected from the group consistingof phenols, phenyls, benzyls, glycols, glycerol, butadienes, carboxylgroups, terpenes, phthalates, anthracenes, isophorenes, plant esters,ketones, amines, glycol ethers, pyrenes, toluenes, heterocycliccompounds, polycyclic aromatic hydrocarbons, mono and di aromatics,polyols, xanthenes, plant essential oils, enzymes from microbes, etc,and combinations thereof.(.) 4) The method according to claim 3, whereinsaid semi-volatile organic compounds are selected from the groupconsisting of phenol, sodium phenate, and glycerol. 5) The methodaccording to claim 1, wherein said liquid mixture further comprises adetergent. 6) The method according to claim 1, wherein said liquidmixture further comprises a surfactant 8) The method according to claim6, wherein said liquid mixture comprises: a) from about 0.25% to about20% said aromatic compounds; b) from about 0.1% to about 3% saidsurfactants; and c) from about 70% to about 99.5% said water. 9) Themethod according to claim 6, wherein said liquid mixture comprises fromabout 0.25% to about 10% aromatic compounds. 10) The method according toclaim 1, wherein the aromatic compounds were emulsified. 11) The methodaccording to claim 1, wherein an area to be treated is under “neutral”air pressure differential. 12) The method according to claim 1, whereinsaid liquid mixture is introduced into said area by a technique selectedfrom the group consisting of misting and fogging.